1. Field of the Invention
The present invention relates to a resin composition. Specifically, the present invention relates to an epoxy resin composition using a polymer solution prepared from an N,O-heterocyclic compound as a modifier, and the applications of the composition in prepregs and printed circuit boards.
2. Descriptions of the Related Art
Printed circuit boards are circuit substrates that are used for electronic devices to load other electronic components and to electrically connect the components to provide a stable circuit working environment. One kind of conventional printed circuit boards is a copper clad laminate (CCL), which is primarily composed of resin, reinforcing material and copper foil. The resin may be, for example, epoxy resin, novolac resin, polyamine formaldehyde resin, silicone resin or polytetrafluoroethylene resin; and the reinforcing material may be, for example, glass fiber cloth, glass fiber mat, insulating paper or linen cloth.
Generally, a printed circuit broad can be prepared using the following method: immersing a reinforcing material such as a glass fiber fabric into a resin; setting the immersed glass fiber fabric to a half-hardened state, i.e. B-stage, to obtain a prepreg; superimposing a certain number of layers of the prepregs and superimposing a metal foil on at least one external surface of the superimposed prepregs to provide a superimposed object; performing a hot-pressing operation onto the superimposed object, i.e. C-stage, to obtain a metal clad laminate; drilling a plurality of holes on the metal clad laminate and plating these holes with a conductive material to form via holes; and finally, etching the metal foil on the surface of the metal clad laminate to form a defined circuit pattern to accomplish the preparation of the printed circuit broad.
In the preparation of prepregs, the resin composition cannot always completely adhere and cover the surface of the reinforcing material, i.e. voids may remain in the interface between the resin composition and the reinforcing material, due to an insufficient wettability of the resin composition. Moreover, if the adhesion of the prepared prepreg to the metal foil is poor, voids will be easily generated in the interface between the prepreg and the metal foil. Such voids may cause electric leakage of the printed circuit board during operation (especially under a high temperature, a high humidity and a high voltage condition) and thus, result in a short circuit.
The present invention provides a resin composition for preparing printed circuit boards, which possesses a good wettability for the reinforcing material (such as a glass fiber cloth) and thus, can avoid voids being generated between the resin composition and the reinforcing material. In addition, the resin composition of the present invention can also improve the adhesion between the prepreg and the metal foil, i.e., can avoid voids being generated between the prepreg and the metal foil, and thus, can avoid short circuiting that results from the voids.